The present invention relates to catheters.
A various assortment of catheters, such as urinary catheters and endotracheal tubes, have been proposed for use in patients. In the case of urinary catheters, Foley catheters are commonly constructed with a shaft having a drainage lumen and an inflatable balloon adjacent a distal end of the shaft. During placement, a distal end of the catheter is passed through the patient's urethra until the balloon and drainage eyes, which communicate with the drainage lumen, are located in the patient's bladder, and the balloon is inflated through an inflation lumen to retain the catheter in place. During catheterization, urine drains through the drainage eyes and lumen and through a drainage tube connected to a proximal end of the catheter to a drainage bag for collection therein.
Conventional catheters of this sort were made from latex rubber through dipping techniques known to the art. In time, it was discovered that the latex catheters were not completely satisfactory since layers of the dipped material occasionally became delaminated during use, thus causing blockage in the inflation lumen and obstructing deflation of the balloon when it was necessary to remove the catheter from the patient. As a result, it became desirable to construct the catheter shaft from a material which may be extruded in order to prevent possible blockage of the inflation lumen, and reduce the cost of the catheter to the patient due to simplified manufacturing techniques.
In turn, the materials which appeared satisfactory for use as a shaft posed new problems in construction of the catheter. For example, it became necessary to find suitable materials for the balloon which are sufficiently elastic to permit inflation during use, and which are compatible with the selected shaft for bonding purposes. Frequently, materials which appeared otherwise satisfactory for the catheter shaft and balloon proved to be incompatible when attempts were made to bond the balloon to the shaft through use of adhesive or sealing. In addition, it became necessary to secure a tip to the distal end of the extruded shaft, and a connector to the proximal end of the shaft. Such tips and connecters have been formed separately, and have been adhered to the shaft. However, in the case of the connecters, it is necessary to establish communication between lumens in the connecter and the associated inflation and drainage lumens in the shaft. In the case of the tips, it is necessary to obtain a sufficient bond of the tip to the distal end of the shaft while closing the distal end of the inflation lumen. In both cases, difficulties have been encountered in obtaining the proper alignment of lumens and achieving the desired bond. In addition, it has been necessary in the past to separately form an opening in the outer surface of the shaft to obtain communication between the inflation lumen and a cavity beneath the balloon. All of the excessive operations and difficulties associated with construction of the catheter deleteriously affect the capability of providing the catheter, which is considered a disposable item, at a significantly reduced cost.